Generally two types of foam applicators are used in current practice—applicator guns (U.S. Pat. No. 5,271,537 (JOHNSON CHARLES W) Dec. 21, 1993) and hand-held applicators.
The first type, applicator guns, is used mainly in professional construction, because an empty cylinder can be replaced with a full cylinder and the work may continue. The second type, so called hand-held applicators, is used mainly in private homes, where smaller quantities of polyurethane foam are needed. The mechanic and physical properties of the foams used with applicator guns and with hand-held applicators are generally different. The valves of the foam cylinders designed for different types of applicators are usually different as well, so that a hand-held applicator cannot be used on a polyurethane foam cylinder designed for applicator guns and vice versa.
In order to use a cylinder with a gun valve, the cylinder is attached to the ball valve of the applicator gun by using a threaded adapter that sits on the cylinder valve. The valve opens as a result of the pressure applied by the valve seat to the border of the valve pin, while the surfaces create a hermetic connection to prevent the pressurised content of the cylinder from going elsewhere than only through the ball valve into the applicator gun. The foam flow rate is controlled by the trigger of the applicator gun. The hand-held applicator is attached to the valve with a thread; the foam flow rate is controlled by tilting the hand-held applicator ( U.S. Pat. No. 4,165,825 (SOUTHERN CAN) Aug. 28, 1979).
Consequently the manufacturers of foam have to order and use in the manufacturing process foam cylinder valves With different designs; i.e., they produce foam cylinders designed for applicator guns and foam cylinders that can be used with hand-held applicator. This complicates the production process compared to a situation where production of only one type of cylinders would suffice.
Document U.S. Pat. No. 3,907,012 (VCA CORP) Sep. 23, 1975, describes a solution for a connecting piece that would enable, for example, leading pressurised gas from a cylinder into a vehicle tyre or other inflatable products. However, this solution is not usable on foam cylinders due to specific nature of polyurethane foam. Document GB 2252132 (WILLIAMS NORMAN) Jul. 29, 1992, describes a solution for a connecting piece that enables to connect different nozzles to an aerosol cylinder. However, this solution is not suitable for using hand-held foam applicators, because it does not provide an opportunity to control the liquid flow rate.
Document WO 2005/070787 (FAZEKAS GABOR ET AL) Aug. 4, 2005, describes a connecting piece for hand-held applicator that is attached onto the foam cylinder, accommodating the valve of the cylinder in its intake port after attachment of the connecting piece. The design enables sealed connection between the connecting piece and the cylinder to prevent the foam from coming into contact with air while leaving the cylinder.
Document GB 2316460 (SELLARS MICHAEL JOHN) Feb. 25, 1998, describes a fastening device for cleaning cylinders. The purpose of the fastening device or connecting piece is to enable cleaning applicators of various designs, i.e., both applicator guns and hand-held applicators can be attached to the cleaning cylinder. The connecting piece includes a threaded part, nipple and details for fixing the connecting piece onto the cylinder. The threaded part is designed to attach an applicator gun to the cleaning cylinder. The nipple enables attachment of a hand-held applicator to the cleaning cylinder. The nipple inside the threaded part is fixed to that part with three bridges. However, this design cannot be used for extracting the foam, because in the case of a hand-held applicator, for instance, the foam would be pressed out from the gaps between the applicator and the connecting piece.